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Biomedical subjects

P Loiseau

Publications and source records attributed to P Loiseau.

At least 181 records · Page 10Linked to original sources
PubMed1985

Evidence for a new HLA class II determinant present on cells from HLA-DR1 and/or -DR4 individuals.

Evidence for a new HLA class II specificity is presented. It is recognized by LE serum, which reacts with most DR1 and/or DR4 individuals (r = 0.86). Its frequency in the French population is 0.33. Absorption-elution experiments showed that the serum reactivity was not due to a mixture of anti-DR1 and anti-DR4 antibodies, but to a single antibody population which could be absorbed on and eluted from both DR1(+) or DR4(+) cells. LE specificity seemed to be expressed on DR but not on DQ molecules since the serum reacted with and could be absorbed by DR+,DQw- cells; it did not react with a DR-,DQw+ mutant cell, but did react with the DR+,DQw+ parental cell. The relationship between LE specificity and MC1 and Te23 specificities remains to be determined.

Adult↗
PubMed1985

Waldenström's macroglobulinemia and peripheral neuropathy: deposition of M-component and kappa light chain in the endoneurium.

Some cases of peripheral neuropathy associated with benign IgM monoclonal gammopathy, or Waldenström's macroglobulinemia, are probably of autoimmune origin; in some cases, anti-IgM serum reacts with the myelin sheaths of peripheral nerves. However, mechanisms may differ in other cases. In one case of neuropathy with macroglobulinemia, we found deposits of IgM immunoglobulin in the endoneurium. On ultrastructural examination, the deposits had erased the basement membrane of some nerve fibers that showed damage of both myelin and axon.

Humans↗
PubMed1985

[Hypermyelination in a case of peripheral neuropathy with benign IgM monoclonal gammopathy].

A 65 year-old man presented with a 8 months history of ataxia and weakness of the lower limbs. Acroparesthesias had been present for ten years in all four limbs. Serum protein electrophoresis showed a monoclonal IgM kappa spike. Bone marrow showed no increase in plasma cells. Motor conduction velocities were reduced. A biopsy from the right superficial peroneal nerve revealed several enlarged myelin sheaths in each fascicle on semi-thin sections. Under electron microscopy these large myelin sheaths were either regularly arrayed around the axon or formed several large additional loops. The outer lamellae of these abnormal myelin sheaths and of the additional loops were frequently widened. Other fibers showed a widening of some myelin lamellae (W.M.L.) with a myelin sheath of varying thickness, and these widened lamellae were frequently joined together. A direct immunopathological study could not be made. The widening of some myelin lamellae is present in most cases of peripheral neuropathy with IgM monoclonal gammopathy and a fixation of anti IgM serum on some myelin sheaths may be demonstrated by direct immunopathology. Hypermyelination has been reported in a few cases. In this patient hypermyelination was as developed as in typical cases of tomaculous neuropathy. An association in some myelin sheaths of hypermyelination and W.M.L. has been noted in serum induced myelin aberrations in peripheral nervous system cultures.

Aged↗
PubMed1985

[Hashimoto's thyroiditis and myoclonic encephalopathy. Pathogenic hypothesis].

A 49 year old caucasian female with Hashimoto thyroiditis, developed during two years a neurological disorder with tonic-clonic and myoclonic seizures and confusional states. Some attacks were followed by a transient postictal aphasia. Some parallelism was noted between the clinical state and TSH levels. Neurological events disappeared with the normalisation of thyroïd functions. This association of Hashimoto thyroiditis and myoclonic encephalopathy has been rarely published. Pathogenesis could be double. Focal signs could be due to an auto-immune mechanism, perhaps through a vasculitis. A non-endocrine central action could explain diffuse signs: tonic-clonic seizures, myoclonus and confusional episodes.

Confusion↗
PubMed1984

Stiripentol kinetics in epilepsy: nonlinearity and interactions.

Stiripentol kinetics during oral therapy were assessed in six patients with epilepsy who were receiving other antiepileptic drugs. Steady-state levels at 600, 1200, and 2400 mg/day increased in a nonlinear fashion, indicating Michaelis-Menten kinetics. Oral clearance of stiripentol at 600 mg/day was 41.5 +/- 23.4 l/day/kg (mean +/- SD), greater than that at 1200 mg/day (20.3 +/- 8.8 l/day/kg; P less than 0.05) or 2400 mg/day (8.5 +/- 3.8 l/day/kg; P less than 0.01). The apparent in vivo Michaelis-Menten parameters were determined from three mean steady-state concentrations. The average velocity of conversion of stiripentol to its metabolites (Vm), Michaelis constant (Km), and the ratio Vm/Km were 49.3 +/- 13.1 mg/day/kg, 1.35 +/- 1.08 mg/l, and 50.2 +/- 27.5 l/day/kg. Stiripentol reduced the elimination clearances of concomitant antiepileptic drugs. Phenytoin clearance was reduced in all five subjects who received this drug, from a mean control of 29.5 +/- 13.4 l/day to 18.5 +/- 4.6 l/day at a stiripentol dose of 1200 mg/day (P = 0.05) and to 6.48 +/- 2.59 l/day at 2400 mg/day (P less than 0.01). Stiripentol reduced the clearance of carbamazepine in one subject from a control value of 209 l/day to 128 l/day (1200 mg/day) and 61 l/day (2400 mg/day). Stiripentol reduced phenobarbital clearance in two subjects from 3.8 and 5.1 l/day to 2.3 and 3.4 l/day (2400 mg/day). The Michaelis-Menten kinetics of stiripentol, as well as its interactions with other antiepileptic drugs, have important implications in the designing of controlled clinical trials.

Administration, Oral↗
PubMed1984

Michaelis-Menten kinetics of stiripentol in normal humans.

Michaelis-Menten kinetic parameters for stiripentol, and anticonvulsant, were assessed in six normal volunteers. Stiripentol was administered orally three times a day in dosage increments of 600, 1,200, and 1,800 mg/day for consecutive periods of 3, 4, and 7 days, respectively. Stiripentol steady-state levels at the three dosing rates increased more than proportionally with dose. The mean +/- SD oral clearance of stiripentol at 600 mg/day (1,090 +/- 624 L/day) was significantly greater (p less than 0.01) than at 1,200 (506 +/- 219 L/day) or 1,800 (405 +/- 151 L/day) mg/day. Average steady-state concentrations predicted from individually determined Vm and Km parameters were in good agreement with experimentally observed levels, indicating that the kinetics of stiripentol are of the Michaelis-Menten type. The mean Vm, Km, and Vm/Km ratio were 2,299 +/- 490 mg/day, 2.20 +/- 1.28 mg/L, and 1,241 +/- 837 L/day, respectively. Neuropsychological tests carried out before and after 14 days of stiripentol treatment showed a significant decline in verbal learning ability (p = 0.038) and a significant improvement in a test of memory and attention (p less than 0.01).

Adult↗
PubMed1984

Carbamazepine/valproic acid interaction in man and rhesus monkey.

Sodium valproate (VPA) was administered for 1 week (1 g b.i.d.) to seven epileptic patients receiving chronic carbamazepine (CBZ) therapy. Steady-state CBZ levels determined before and after VPA therapy were reduced by 3-59% in six patients and were unchanged in one patient. The plasma concentration ratio of carbamazepine-10,11-epoxide ( CBZE ) to CBZ increased in all patients by 11-500%. The plasma binding of CBZ was determined in six healthy volunteers given a single 400 mg CBZ dose with and without the coadministration of 1 g VPA in a cross-over design. The mean CBZ free-fraction was increased in three of the subjects (p = 0.008-0.031), decreased in one subject (p less than 0.002), and remained unchanged in two subjects when VPA was administered. Four male rhesus monkeys were infused intravenously with CBZ (15 mg h-1) for 5 days and then three consecutive 24-h infusions were given: I, CBZ alone; II, CBZ with 75 mg h-1 VPA; III, CBZ with 150 mg h-1 VPA. The mean free-fraction of CBZ and CBZE increased during infusions II and III from 31.5 +/- 2.7% to 33.6 +/- 2.6% (p less than 0.05) and 37.7 +/- 1.3% (p less than 0.01) for CBZ and from 46.9 +/- 9.2% to 53.6 +/- 5.7% (p greater than 0.05) and 60.1 +/- 4.0% (p less than 0.01) for CBZE . The clearance of free CBZ declined from 7.96 +/- 1.75 to 4.84 +/- 1.26 (p less than 0.01) and 4.12 +/- 1.75 (p less than 0.01) 1 kg-1h-1 during infusions II and III, respectively. The mean free CBZE /CBZ ratio increased from 0.12 +/- 0.03 to 0.24 +/- 0.03 and 0.36 +/- 0.04 during infusions II and III, respectively (p less than 0.001). These findings indicate a decrease in the elimination clearance of CBZE possibly coupled with a decrease in its formation clearance.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1984

[Partial epilepsies of adolescence with computer tomography abnormalities, localized astrocytic reaction and spontaneously remitting course].

Four teenagers with partial epileptic seizures presented focal cortical enhanced CT scan images. Angiographies were normal. Stereotactic biopsies revealed astrocytic proliferation. CT scan abnormalities diminished or vanished in some months. On long-term follow-up seizures were either less frequent or disappeared. None of the possible aetiologic hypotheses (astrocytoma, encephalitis, sarcoidosis, multiple sclerosis, vascular malformation) was fully satisfying. Nevertheless, a regressive evolution observed in these four patients demonstrates that acquired epileptogenic lesions during adolescence are not always of poor prognosis.

Adolescent↗
PubMed1984

[Efficacy of sodium valproate in partial epilepsy. Crossed study of valproate and carbamazepine].

An open response-conditional cross-over study of valproate versus carbamazepine has been done in previously untreated patients with partial seizures. Thirty-one patients entered the study. Nineteen were followed up to one year. It appeared that valproate was at least as effective as carbamazepine: at one year, 11 patients were seizure-free on valproate and only 8 were seizure-free on carbamazepine. Furthermore no side-effect was noted in valproate therapy, whereas carbamazepine was stopped in 2 patients because of skin rashes. The efficacy of sodium valproate in partial epilepsy remains controversial. It is of course limited when given as co-therapy in severe epilepsies, uncontrolled with other major antiepileptic drugs. However in naive patients, with recent and previously untreated partial epilepsies, a one-drug treatment with valproate appears to be as effective as carbamazepine or phenytoin. It has less unwanted side-effects and should be prescribed as first line treatment.

Adolescent↗